LiFePO4 vs AGM Batteries for Vanlife
The choice of leisure battery technology is one of the most consequential decisions in a campervan electrical build. Get it right and your system is reliable, lightweight, and low-maintenance for years. Get it wrong and you end up with a battery that underdelivers, degrades faster than expected, or fails in cold weather when you need it most. This guide compares the two most relevant battery technologies for 2025 van builds in honest, practical terms: Lithium Iron Phosphate (LiFePO4) and Absorbed Glass Mat (AGM).
Technology Overview
AGM (Absorbed Glass Mat)
AGM is a type of valve-regulated lead-acid (VRLA) battery. The electrolyte is absorbed into fibreglass mat separators rather than being free liquid, which makes the battery spill-proof and maintenance-free. AGM batteries have been the standard leisure battery technology for campervans, motorhomes, and boats for decades. They are well-understood, widely available, and relatively inexpensive.
AGM performs well in the slow-discharge, slow-recharge duty cycle typical of campervans. They tolerate temperature extremes better than lithium in one direction (they can be charged at 0 °C, unlike lithium which requires a heated BMS or specific low-temperature chargers), and they are robust against overcharging in a way that lithium is not.
LiFePO4 (Lithium Iron Phosphate)
LiFePO4 is one of several lithium-ion chemistries, chosen for leisure applications specifically because it is the most thermally stable and safest lithium variant. Unlike NMC or NCA lithium (used in electric vehicle packs and consumer electronics), LiFePO4 does not enter thermal runaway under normal abuse conditions and has no meaningful risk of fire in a correctly installed system. This distinction is important — "lithium battery" is not a generic term, and the safety characteristics differ significantly between chemistries.
LiFePO4 batteries include a built-in Battery Management System (BMS) that protects against overcharge, over-discharge, excessive current, and short circuit. The BMS is not optional — it is the safety and management layer that makes the chemistry practical in a vehicle application.
Usable Capacity and Depth of Discharge
The most significant practical difference between LiFePO4 and AGM is the usable proportion of the rated capacity.
AGM batteries should not typically be discharged below 50% of their rated capacity. Discharging an AGM battery to 80% depth of discharge (DoD) regularly will dramatically shorten its service life — the plates sulphate prematurely and capacity fades quickly. In practice, from a 100 Ah AGM battery, you have around 50 Ah of reliable, repeated-use capacity.
LiFePO4 batteries can be discharged to 80–90% DoD without meaningful lifespan impact. Most manufacturers specify 80% DoD for cycle life ratings, and some quote 100% DoD as acceptable for occasional use. In practice, from a 100 Ah LiFePO4 battery, you have 80–90 Ah of usable capacity.
This means a 100 Ah LiFePO4 battery delivers roughly 60–80% more usable energy than an equivalently rated AGM. To achieve the same usable capacity as a 100 Ah lithium, you need approximately 160–200 Ah of AGM.
Lifespan and Cycle Count
Battery lifespan is typically quoted in charge-discharge cycles to 80% remaining capacity.
| Battery Type | Typical Cycle Life (to 80% capacity) | DoD Assumption |
|---|---|---|
| AGM (quality, e.g. Victron, Exide) | 400–600 cycles | 50% DoD |
| AGM (budget) | 200–350 cycles | 50% DoD |
| LiFePO4 (quality, e.g. Victron, Lishen, Eve) | 2,000–4,000 cycles | 80% DoD |
| LiFePO4 (budget, known cell brands) | 1,500–2,500 cycles | 80% DoD |
If a van is used 150 nights/year with a daily discharge-charge cycle, a quality AGM bank will last roughly 3–4 years. A quality LiFePO4 bank will last 13–26 years under the same conditions — far beyond the realistic service life of most campervans.
Weight
Lead-acid chemistry is inherently heavy. A 100 Ah AGM battery typically weighs 27–32 kg. To achieve 200 Ah of usable AGM capacity (requiring 400 Ah nominal), you are carrying 108–128 kg of batteries. In a campervan, this is a significant payload penalty and affects handling.
A 100 Ah LiFePO4 battery weighs approximately 12–15 kg. For the same 200 Ah of usable capacity, you need 250 Ah nominal LiFePO4, weighing approximately 32–40 kg. The weight saving is 70–85 kg for an equivalent-performance system — meaningful for a light commercial van with a 900 kg payload rating.
Charge Speed
LiFePO4 batteries accept charge much faster than AGM. A quality LiFePO4 cell can accept charge at up to 0.5C (meaning a 100 Ah battery can be charged at up to 50 A) without damage, and many BMS units allow even higher rates for short periods. AGM batteries should not typically be charged above 0.2C (20 A for a 100 Ah battery) to avoid damage from gassing.
In practical terms: if you drive for two hours and want to recharge your battery bank, a LiFePO4 system with a 40 A DC-DC charger will put back 80 Ah in those two hours. An AGM system with the same charger should be limited to 20 A (or the bank will be damaged), putting back only 40 Ah.
Cold-Weather Performance
Cold weather is the area where LiFePO4 has a genuine weakness. LiFePO4 cells can discharge at temperatures as low as -20 °C, but they must not be charged below 0 °C (some cells allow charging to -10 °C at reduced rates). Charging a lithium battery at sub-zero temperatures causes lithium plating on the anode, which permanently damages the cell and reduces capacity.
Quality LiFePO4 batteries for leisure use (Victron, Fogstar, Epoch, Battle Born, Renogy) include a low-temperature charge cut-off in the BMS — the battery simply refuses to accept charge when it is too cold. In a van parked in winter conditions, the battery may be fine but the BMS will not allow morning recharging until the cells warm up (either from being inside a heated van or from self-heating BMS options in premium products).
AGM batteries can be charged at 0 °C and perform reasonably well at moderately cold temperatures, though capacity reduces at low temperatures. A well-charged AGM in a 0 °C van overnight will have around 80–85% of its rated capacity available.
For UK, German, and Dutch winters — where temperatures frequently reach -5 to -10 °C — a self-heating LiFePO4 battery or one housed in the heated living space is the correct solution. A battery in an unheated external locker is at risk of BMS lockout on cold mornings.
Battery Management System (BMS)
Every LiFePO4 leisure battery includes a BMS. The quality of the BMS varies significantly between manufacturers and has a major effect on reliability and safety. Key BMS functions to look for:
- Cell balancing: Keeps individual cells within the pack at equal state of charge. Without this, cells diverge and overall capacity degrades.
- Over-voltage protection: Disconnects charge if voltage exceeds safe limits.
- Under-voltage protection: Disconnects load if cells are over-discharged.
- Over-current/short-circuit protection: Shuts off in fault conditions.
- Temperature protection: Prevents charging below 0 °C and discharging above 60 °C.
- Bluetooth monitoring: Available on premium batteries — allows real-time state-of-charge monitoring from a phone app.
Total Cost of Ownership Over 10 Years
AGM looks cheaper at purchase. Over 10 years of regular use, the picture changes significantly.
| Metric | AGM (200 Ah usable) | LiFePO4 (200 Ah usable) |
|---|---|---|
| Nominal capacity required | 400 Ah (2 × 200 Ah) | 250 Ah (1 × 250 Ah) |
| Initial purchase cost | £350–£500 | £700–£1,100 |
| Expected service life (150 cycles/year) | 3–4 years | 13–20+ years |
| Replacements needed over 10 years | 2–3 | 0 |
| 10-year total battery cost | £700–£1,500 | £700–£1,100 |
| Weight (for 200 Ah usable) | 108–128 kg | 32–40 kg |
| Cost per cycle (quality brands) | £0.50–£0.80 | £0.18–£0.35 |
The 10-year total cost of ownership for AGM and LiFePO4 is often similar or even lower for lithium when replacements are factored in. The weight saving, higher usable capacity per nominal Ah, and faster charge acceptance make LiFePO4 the objectively better technology for most full-time and frequent van use.
When AGM Still Makes Sense
Despite LiFePO4's advantages, there are situations where AGM remains a rational choice:
- Budget-constrained builds: If upfront cost is the primary constraint and the van will be used only occasionally, AGM is a workable solution. A quality 110 Ah AGM leisure battery costs £100–£180, versus £350–£600 for a comparable LiFePO4 unit.
- Cold-climate storage: If the van sits in an unheated garage or outdoor storage through a northern European winter, AGM batteries can be trickle-charged safely. LiFePO4 in very cold conditions requires a heated storage solution or will not accept charge.
- Existing AGM system replacement: If your existing charging setup (alternator and solar charge controller) is tuned for AGM voltages and you are simply replacing a failed battery, like-for-like AGM replacement avoids the need to reconfigure the system.
- Short, infrequent trips: A weekend campervan used 20–30 times per year for short trips where hook-up is available has very modest battery demands. AGM at 50% DoD may be entirely sufficient.
Frequently Asked Questions
Can I mix LiFePO4 and AGM batteries in the same bank?
No. Different battery chemistries have different charge voltages, internal resistances, and discharge curves. Mixing them in the same bank causes one type to be chronically over- or under-charged, damaging both. Use a single chemistry in each battery bank. You can have separate banks for separate purposes (e.g. a starter battery and a lithium leisure bank) provided they are charged separately.
Do I need to change my solar charge controller if I switch to LiFePO4?
Only if your existing controller cannot be configured for lithium charge profiles. Most quality MPPT controllers (Victron, Epever, SRNE) include a lithium charge profile setting. AGM charge voltages (typically 14.4–14.7 V absorption, 13.6 V float) differ from LiFePO4 (14.2–14.6 V absorption, no float needed or 13.5 V float). Check your controller's specifications before switching chemistry.
Is a 12V or 24V battery system better for campervans?
12V is standard for most van builds and gives you the widest choice of compatible appliances, chargers, and inverters. 24V systems are more efficient for high-power applications (large inverters, powerful DC loads) but require 24V-compatible equipment throughout. Most leisure vehicle builds use 12V.
How do I know if my LiFePO4 battery BMS has tripped?
A BMS trip typically manifests as the battery appearing dead — zero voltage at the output terminals despite the battery not being fully discharged. On batteries with a Bluetooth monitoring app, the BMS status is visible directly. On others, check the BMS indicator light (if present), check cell voltages with a multimeter if accessible, and review whether a low-temperature, over-current, or over-voltage condition could have caused the trip. Many BMS units reset automatically once the fault condition is resolved.
What is the maximum recommended age for an AGM leisure battery?
Regardless of cycle count, most quality AGM batteries degrade over time due to sulphation and grid corrosion. For a campervan used regularly, replacing AGM batteries every 3–5 years is prudent. If capacity testing shows more than 20% capacity loss from new, replacement is due regardless of age.
